Question

When a body is stationary, then
(A) There is no force acting on it
(B) The body is in vacuum
(C) The forces acting on it are not in contact with it
(D) The net forces acting on it balance each other

Answer 1

Hint: Body is stationary i.e., means body is not moving i.e., it is at rest for explaining this concept we can use Newton's first law of motion. Which is the law of inertia or we can use the relation between velocity, acceleration and force.

Complete step by step solution:
When a body is stationary then its velocity is zero. Hence, its acceleration is zero and net force on the body will also be zero because.
$\Delta = \dfrac{{dv}}{{dt}} = 0$
$F = ma = 0$

Now we have to check all the options one by one.

(A) There is no force acting on it.
Above statement is correct only in some limited conditions, not always. So, (A) is not correct answer

(B) The body is in vacuum
There is no role of vacuum here because the vacuum body cannot remain stationary. So, (B) is not the correct answer.
(C) The forces acting on it are not in contact with it
Body motion does not depend on contact force it depends on net force acting on it. So, (C) is not the correct option.

(D) The net forces acting on it balance each other.
For the body to be stationary, net external force acting on it must be equal to zero which is possible only when the combination of forces acting on it balance each other.

So, (D) is the correct answer.




Note: If the body is at rest, then external forces are balanced between each other. If net external force is not zero then the body will be in moving condition.